Test methods and devices

A method and test device for differentiating between states of an analyte that can exist in different forms, such as follicle stimulating hormone (FSH). The method or test device uses a pair of specific binding agents, especially monoclonal antibodies, in two assays for the same analyte. The assays, applied to contemporaneous samples, differ from one another in format, one being a two step assay and the other being one step. A novel pair of anti-FSH monoclonal antibodies that can be used together in two such assays to differentiate pre-menopausal and post-menopausal FSH samples is disclosed.